Specific aims include the following: (a) to test the effect of MIX (1-methyl-3-isobutyl xanthine) in vivo, in mice with heriditary nephrogenic diabetes insipidus; (b) to measure plasma concentrations and rates of urinary excretion of vasopressin, oxytocin, and prostaglandins in humans and mice with nephrogenic diabetes insipidus; (c) to trace, in rats and mice, vasopressinergic and oxytocinergic axons that run outside of the hypothalamus; (d) to further explore, in rats, the mechanisms that depress renal hemodynamics during anesthesia; (e) to follow the time course of renal function (GFR, RPF, salt excretion) during the development of high blood pressure in spontaneously hypertensive rats; (f) to continue our search for the precursors of oxytocin, vasopressin, and their associated neurophysins; and (g) to apply radioimmunoassays for human neurophysins to the management of patients with small cell carcinoma of the lung.